Dental bridgework.



C. EL EHATT.

DENTAL HFHDGEWHK.

APPLICATION FILED SEPT. 7x 191s.

.Patented July 3l, 1917.

WITH ESS CHARLES-B. BRATT, 0F PITTSBURGH, PENNSYLVANIA.

DENTAL BRIDGEWORK.

Application led September 7, 1916.

To all whom t may concern.'

Be it known'thet I, CHARLESy B.V BnA'rT, a citizen of the United States, residing at Pittsburgh, in the county of Alleghenyr and State of Pennsylvania, have 'invented certain new 'and useful Improvements in Dental Bridgework, of Which the following is a specification.

The invention relates to dentalbridge- Work ondparticularly to the means for securing a connection between porcelain teethand the metal backing plates employed therewith. The invention has for its pri mary objects; the provision Aot' :i construction (l) wherein the cutting of the porcelain is distributed in such manner :is to reduce the danger of splitting or cracking, (2) wherein the central portions ct the `tooth is left of maximum strength., und (3) which` can be cheaply and accurately nitide. Certain embodiments of the invention :ire

illustrated in. the accompanying drawings,

` 4; Figs. 7 `and 8 are rear face and end elevation views respectively, of a modification;

Figs. 9 and 10 are :i face view and @ed elevation respectively, of checking for use in connection'with the tooth of Figs. 7 sind 8;

11 and 12 are rear fece and end eleva- ;-tion views respectively'of' another "modification; Figs. 13 and 14 are a face view and end elevation respectively, of o backing for use in connection with the tooth of Figs. 11. and 12; and Fig. 15 is e transverse section through still .another modification.

Referring rst to the construction voit' Figs which may be of any desired conigurtion and which is provided on its rear side With a pair'of longitudinally extending grooves= each comprising the portion 2, circular in crosssection, sind the slot V3, which slot 43, as indicatedin Fig. 2, is of less length. than the larger circular portion of the groove beneath. A backing plate 4 (Figs. 5 and 6) is ,used in connection with this tooth, such Vbacking comprising a metallic plete prefen that f the grooves. The tapered form of' 1, 2, 3 and 4, 1 is e. porcelain tooth` Specification of Letters latent.

Patented July 31,1917'.

Serial No. 118,828.

of the circular portion 5, es indicated in dotted lines in Fig. 5, so that when the back ing is applied. to the tooth the end of thel circuler portion o extends to the inner end of the circuler portion 3 of the groove in the tooth, so that a very secnri support at the inner end of the rib is secured.

This form of construction is advantageous since the tooth is not weakened along the center' line A by the cutting of the grooves. und it is :it the center .line that breakage ordinarily occurs with teethoii 'this clizirocterf The grooif'es irre erich locirted` intermediate tlxe center line of the tooth and its outer edge, ond een be made much smaller in "-section than where only e. single groove ed has heretofore been the practice moet ceses. The infr-king of the bottom Di' "tions 2 of the grooves `renier also eliminates the dmiger ci bres ing or cracking, 4 l.suoli-1s present Where grooves having sharp corners .are employed. l'. Will also be seen that relatively smell grooves of 'this cherectcr can oe spaced :i relatively greet distance froin the center line of the tooth, thus giving e` better resistance against twist-l ing strain than is the case where the grooves :ire necessarily placed relatively close to the center line of the tooth. Another edwinV tage in this construction consists in, the ease with which the grooves een be cored out and subsequently remixed to the exact size de sired, it being much easier vto cut groove substantially circuler in crossection than one having an angular cross-section. 4Other advantages incident to my construction will he readily apparent to those skilled, in the art.

In the construction of Figs. 7 and 8 the grooves 7 are the saine as in the irst con'- struction except that the circuler portions of these grooves are tethered, es indicated in. dotted 'lines in Fig. 7. The boeking 8 enr-- plcyed with this construction is providedl `with ribs having tapered circular portions 9 and necks 1,0 connecting theni with the platethe,.sha pe of the ribs corresponding to ict' the. ribs gives the most advantageous distribution ofnietal with respeet to the strain 'imposed thereon.

Figa. l1 and 12 illustrate still another .z'noclilieation wherein. the eirenlar portions Il of the grooves have their center line-.sI inelined with respeet to th'e center line of the tootl'i, as indicated in the dotted lines, Fig. ll, the angle of vinclination ap roxilnating that of the .sides of the tooth; V`he slot portions 12 olf the grooves are parallel to eaeh other ae. are also the o-nter side Wallel 1H of the eireular portions il. rlhe haeking 14 used with this tooth is Provided with tapered lribs l5 having their vrenter lines in elined to correspond with those of the grooves. The neck )ortions'lG ol.' the ribs are parallel. The e gea of the slots l2 and .ielika 16 are rounded or 'provided with fillets as indicated in Figs. 12 and 14, thus differiti' slivhtl from the Vn'evions conatriietions in which the corners ol' these portions are "left, relatively Sharp. The inclining ofthe grooves and pins gives a still. better support for the tooth than that Secured .in the preceding eonstraetions, the arrangement being 'preferable in this respect to that of the other .f'onstruetions, althoughsomwhat more dillienll. to make.

Fig. l5 illustrates the f-ross-seetion of still another inmliliealion wherein the tooth 17 is provided with grooves 1H, the eireulal' pori ion of zarh grooves being oil' echter with resort-t to the alot portions.

What l rlaiin is:

A tooth zonalraetion comprising a. porcelain tooth providml on its rear Side with a pair of' grooves, eaeh exten-ding longitudinally olt the oolh l'roin its hatt and lying intermediate the eenter line of the tooth and its edge and having their inner Sides and their eenter lines .inclined awa)I from the eenter line ol' the tooth hut with their ohter sidey ederal parallel. thereto,y and having their upper portion,1 relatively narrow with ,their lower portionsh larger in eross-seetion and substantially eirrular tapering t0 a less dialneter fronr the butt end inward, and a hacking provided with a pair of ribs for engagii-ig theosaid grooves. the said ribs having their center lines and inner sides inclined away from eaeh other but with their outer sides parallel.

CHARLES B. BRATT. 

